Sashiko reports for races and possible crash around the usage of est_cpulist_valid and sysctl_est_cpulist. The problem is that we do not lock est_mutex in some places which can lead to wrong write ordering and as result problems when calling cpumask_weight() and cpumask_empty().
Fix them by moving the est_max_threads read/write under locked est_mutex. Do the same for one ip_vs_est_reload_start() call to protect the cpumask_empty() usage of sysctl_est_cpulist. Link: https://sashiko.dev/#/patchset/20260331165015.2777765-1-longman%40redhat.com Fixes: f0be83d54217 ("ipvs: add est_cpulist and est_nice sysctl vars") Signed-off-by: Julian Anastasov <[email protected]> --- Note that this patch complements v2 of patchset from 31-MAR-26 "ipvs: Fix incorrect use of HK_TYPE_KTHREAD housekeeping cpumask" and can be applied before it to avoid the bad AI reviews: https://lore.kernel.org/all/[email protected]/ net/netfilter/ipvs/ip_vs_ctl.c | 5 +++++ net/netfilter/ipvs/ip_vs_est.c | 22 +++++++++++++++------- 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index caec516856e9..8778e174ef56 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1812,11 +1812,16 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u, *svc_p = svc; if (!READ_ONCE(ipvs->enable)) { + mutex_lock(&ipvs->est_mutex); + /* Now there is a service - full throttle */ WRITE_ONCE(ipvs->enable, 1); + ipvs->est_max_threads = ip_vs_est_max_threads(ipvs); + /* Start estimation for first time */ ip_vs_est_reload_start(ipvs); + mutex_unlock(&ipvs->est_mutex); } return 0; diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c index 433ba3cab58c..6c9981d5611e 100644 --- a/net/netfilter/ipvs/ip_vs_est.c +++ b/net/netfilter/ipvs/ip_vs_est.c @@ -68,6 +68,10 @@ and the limit of estimators per kthread - est_add_ktid: ktid where to add new ests, can point to empty slot where we should add kt data + - data protected by service_mutex: est_temp_list, est_add_ktid + - data protected by est_mutex: est_kt_count, est_kt_arr, est_max_threads, + sysctl_est_cpulist, est_cpulist_valid, sysctl_est_nice, est_stopped, + sysctl_run_estimation */ static struct lock_class_key __ipvs_est_key; @@ -229,6 +233,8 @@ static int ip_vs_estimation_kthread(void *data) /* Schedule stop/start for kthread tasks */ void ip_vs_est_reload_start(struct netns_ipvs *ipvs) { + lockdep_assert_held(&ipvs->est_mutex); + /* Ignore reloads before first service is added */ if (!READ_ONCE(ipvs->enable)) return; @@ -304,12 +310,17 @@ static int ip_vs_est_add_kthread(struct netns_ipvs *ipvs) void *arr = NULL; int i; - if ((unsigned long)ipvs->est_kt_count >= ipvs->est_max_threads && - READ_ONCE(ipvs->enable) && ipvs->est_max_threads) - return -EINVAL; - mutex_lock(&ipvs->est_mutex); + /* Allow kt 0 data to be created before the services are added + * and limit the kthreads when services are present. + */ + if ((unsigned long)ipvs->est_kt_count >= ipvs->est_max_threads && + READ_ONCE(ipvs->enable) && ipvs->est_max_threads) { + ret = -EINVAL; + goto out; + } + for (i = 0; i < id; i++) { if (!ipvs->est_kt_arr[i]) break; @@ -485,9 +496,6 @@ int ip_vs_start_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats) struct ip_vs_estimator *est = &stats->est; int ret; - if (!ipvs->est_max_threads && READ_ONCE(ipvs->enable)) - ipvs->est_max_threads = ip_vs_est_max_threads(ipvs); - est->ktid = -1; est->ktrow = IPVS_EST_NTICKS - 1; /* Initial delay */ -- 2.53.0
